Apparatus for applying adhesive to a moving web



Feb. 14, 1967 c. D. NlTCHlE 3,303,814

APPARATUS FOR APPLYING ADHESIVE TO MOVING WEB Filed July 28, 1964 2 Sheets-Sheet 1 INVENTOR. CHHELEs 0. N1 70/15 ,4 TTOEA/E Y.

Feb. 14, 1967 c, D, NlTCHlE 3,393,814

APPARATUS FOR APPLYING ADHESIVE TO A MOVING WEB Filed July 28, 1964 2 Sheets-Sheet 2 INVENTOR. C mqzL 5 0. A/J'TCI/JE Jzz's 17 7 TOP .5. 7:

United States Patent 3,303,814 APPARATUS FOR APPLYING ADHESIVE TO A MOVING WEB Charles D. Nitchie, Baltimore, Md., assignor to Koppers Company, inc, a corporation of Delaware Filed July 28, 1964, Ser. No. 385,628 2 Claims. (Cl. 118249) This invention relates to apparatus for applying a thin coating to a moving sheet and more particularly to apparatus for applying a thin film of adhesive to a continuously moving Web of paperboard.

In the manufacture of corrugated paperboard it is customary to apply adhesive to the crowns of a corrugated web by means of an applicator mechanism that includes a pair of metallic rollers, one or both of the rollers being partially submerged in a reservoir of adhesive. Usually one of the rollers is considered the coating roller and the other the doctor roller. The rollers are arranged in parallel relation to each other with the coating roller in juxtaposition with the crown portions of the corrugated sheet. The coating roller is spaced slightly from the doctor roller to form a nip therebetween. The adhesive picked up from the reservoir by the coating roller passes between the doctor roller and the coating roller and forms a relatively thin film of adhesive on the coating roller. The adhesive film usually has a thickness of about 0.01 inch. The adhesive film is then transferred to thecrown portions of the corrugated sheet as the coating roller contacts the moving corrugated web. A liner sheet is applied to the corrugated web and secured thereto by the adhesive film. Certain of the applicator mechanism include means to adjust the spacing of the rollers relative to each other to thereby, within limits, control the thicknes of the adhesive film applied to the corrugated sheet. It is not possible, however, to obtain a continuous film of adhesive on the coating roller that has a thickness less than 0.006 inch with the applicator mechanisms now used.

The above described applicator mechanism has proved satisfactory for the application of conventional adhesives such as starch and sodium silicate Where the adhesive is inexpensive and a relatively thick film of adhesive is employed. The known applicator mechanisms are not suitable for use with the recently developed adhesives that provide a superior bond with a much thinner film than is required for conventional adhesives. For example, such adhesives as the starch emulsions and polyvinyl alcohols firmly bond a corrugated web to liner sheets When applied in thicknesses that range from 0.005 inch to 0.001 inch. The advantages of an applicator mechanism capable of continuously applying a thin film having the above range of thicknesses is readily apparent. The applicator would make it economically feasible to use the newer, but more expensive adhesives and would improve the overall qual ity of the paperboard. The present invention eliminates the difficulties of presently known applicator mechanisms and now makes it economically feasible to use the newer, more expensive adhesives in film thicknesses not before possible.

Briefly, the invention includes a coating roller that has a peripheral covering of elastomeric material such as rubber or the like. The coating roller is arranged to be partially submerged in an adhesive bath and to have its upper peripheral portion in juxtaposition with the crowns of the moving corrugated web to thereby transfer the film of adhesive to the corrugated web. A pressure roller is positioned parallel to and in juxtaposition with the coating roller. The pressure roller is preferably rigid and has an embossed peripheral surface. The adhesive adhering to the coating roller, as it enters the nip between the coating roller and the pressure roller, is squeezed therebetween and reduced to a thin film having an embossed configuration similar to that of the pressure roller. With certain adhesives having a relatively low viscosity, the embossed film spreads out into a smooth thin film as the coating roller transfers the adhesive to the crowns of the corrugated web. There is also provided a means to move the pressure roller toward and away from the coating roller to flex or distort the elastomeric peripheral covering on the coating roller and thereby control the effective thickness of the film.

Accordingly, an object of the present invention is to provide apparatus for applying a smooth thin coating of liquid adhesive of controlled thickness to the surface of a corrugated web by squeezing an uneven film of adhesive into a thin film of embossed configuration and thereafter transferring the film to the corrugated web.

These and other objects and advantages of this invention will be more completely disclosed and described in the following specification, the accompanying drawings and the appended claims.

In the drawings:

FIGURE 1 is a diagrammatic representation of the preferred apparatus for applying a thin film of adhesive to the crown portions of a moving corrugated web.

FIGURE 2 is a diagrammatic enlarged view illustrating the embossed surface of the pressure roller and the manner in which the film of adhesive assumes the embossed configuration at the nip between the pressure roller and the resilient surface of the coating roller.

In FIGURE 1 there is diagrammatically illustrated apparatus for manufacturing double faced corrugated paperboard that utilizes the apparatus of the present invention.

A single faced corrugated sheet 24 passes through'an adhesive applicator diagrammatically illustrated and generally designated by the numeral 34 that applies adhesive to the crown portions of the single faced corrugated web. A second liner 36 passes around a guide roller 38 that presses the second liner 36 against the adhesive coated crown portions of the single faced corrugated web to form a double faced corrugated web 40. The double faced corrugated web 40 is thereafter further treated in a conventional manner.

The adhesive applicator generally designated by the numeral 34 includes a coating roller 42 that is rotatably supported on a shaft 44. The coating roller 42 has a peripheral covering or surface 46 of elastomeric material such as rubber or other synthetic elastomcr that is resilient and deformable under a compressive force. A metal pressure roller 48 is positioned parallel to the coating roller 42 and has an embossed peripheral surface 50 composed of regularly spaced grooves or recesses with raised portions or protuberances therebetween, as will be described later in detail. The pressure roller 48 is rotatably mounted on an eccentric mechanism 52 in a manner that the roller 48 may be moved toward and away from the coating roller 42. Suitable means are provided to rotate the respective rollers 42 and 4 Beneath the rollers 42 and 48 there is a reservoir 54 in which a supply of adhesive 56 is retained. A portion of the coating roller 42 is submerged in the liquid adhesive. Although the pressure roller 43 is illustrated as being positioned above the upper surface of the adhesive 56, it should be understood that the adhesive applicator will work equally well with both rollers 42 and 48 being partially submerged in the adhesive bath.

The coating roll 42 with the thin film of adhesive thereon rotates in a counter-clockwise direction as illustrated in FIGURE 1. A transfer roll 88 contacts the peripheral surface of coating roll 42 and the thin film of adhesive is transferred from the peripheral surface of coat ing roll 42 to the peripheral surface of transfer roll 88. The transfer roll 88 is so positioned that the crown portions 60 of the corrugated Web 24 contact the upper portion of transfer roller 88. Rider roll 62 urges the corrugated web 24 downwardly so that the crown portions 60 contact the upper portions of transfer roll 88. The thin film of adhesive that is transferred to roll 88 from roll 42 is thereafter transferred to crown portions 60 of web 24. Since transfer roll 88 is a rigid steel roll, it is less subject to wear due to continued contact with the crown portions 60 of moving web 24.

Adjacent to and parallel with the rollers 42 and 48, the guide roller 38 is rotatably supported on a shaft 58. The liner 36 passes around the guide roller 38 and is adhesively secured to the exposed crowns 60 of the single faced corrugated sheet 24. Positioned above the single faced corrugated sheet 24 is a rider roller 62 that is pivotally supported on shaft 64 by means of arm 66. The rider roller 62 is arranged to urge the single faced corrugated sheet 24 downwardly into contacting relation with the transfer roller 88. A spring 68 controls the downward force or pressure exerted by the rider roller 62. The coating roller 42 rotates in a counter-clockwise direction as viewed in FIGURE 1 and, as it passes through the adhesive 56, picks up a quantity of adhesive on its peripheral surface in the form ofoan irregularly shaped film. The film enters the nip 70 between the coating roller 42 and the pressure roller 48 where an excess of the adhesive is returned to the reservoir 54 and a thin film of adhesive remains on the coating roller 42. The coating roller 42 then deposits the thin film of adhesive on the surface of transfer roller 88 which then transfers the film on the crown portions 60 of the single faced corrugated sheet 24. The liner 36 passing around guide roller 38 is moved into contact with the crowns 60 and is adhesively bonded thereto.

The configuration and arrangement of the pressure roller 48 and the coating roller 42 provides an applicator mechanism that forms a thin film of adhesive on the coating roller 42 which is then transferred via the transfer roller 88 to the crown portion 60 of the single faced corrugated web 24. FIGURE 2 illustrates in detail how the rollers 42 and 48 form the thin film of adhesive on the coating roller 42. The pressure roller 48 is mounted in juxtaposition with the coating roller 42 and the rollers 42 and 48 are arranged to rotate in opposite directions and form a nip 70 therebetween. The pressure roller 48 has an embossed peripheral surface that includes a plurality of rectangular recesses 72 that have raised portions or protuberances 74 therebetween. The pockets or recessed portions 72 are separated from each other by the raised portions 74 or the planar portion of the roller peripheral surface 50. For clarity, the portions 74 between the recessed portions 72 will be designated as protuberances 74. It should be understood, however, that the recessed portions or pockets 72 may be formed or engraved in a roller having a smooth peripheral surface so that the division walls between the pockets are a part of the smooth surface of the roller. The recesses 72 illustrated in FIGURE 2 preferably have incline-d surfaces 76 that form the sides of a pyramidal recess. Other configurations of the recessed portions 72 and the protuberances or raised portions 74 may be utilized without departing from the scope of this invention.

The coating roller 42 has an elastomeric surface or covering 46 that is resilient and deformable under compressive pressure. The pressure roller 48 is mounted by means of an eccentric device 52 so that it can be moved toward and away from the coating roller 42. In FIG URE 2 the pressure roller is illustrated as abutting the peripheral surface of the coating roller 42 and slightly deforming the elastomeric peripheral surface 46 to any substantial extent. In FIGURE 2 the adhesive 56 is illustrated adhering to the peripheral surface of the coating roller 42 as a relatively uneven film 78 between the supply of adhesive 56 in the reservoir 54 and the nip 70 formed by rollers 42 and 48. As the uneven film of adhesive 78 enters the nip 70 it is squeezed between the rollers 42 and 48 so that it fills the recesses 72 in the embossed surface 50 of pressure roller 48 that con tacts the elastomeric surface 46 of coating roller 42. The protuberances 74 limit the amount of adhesive that passes from the nip 70 between the rollers 42 and 48. As the rollers 42 and 48 rotate, a thin film 80 remains on the coating roller 42. The thin film 80 has an external surface with recessed portions 82 and protuberances 84. The protuberances 84 have substantially the same shape as the recessed portions or pockets 72 on the pressure roller 48. With certain adhesives that have a relatively low viscosity, the adhesive in the thin film 80 gradually flows into the recessed portions 82 to form a thin film have a substantially smooth surface 86. However, to assure the formation of a very thin film, as where as high viscosity adhesive is used, the adhesive is squeezed between roller 42 and transfer roller 88 which is positioned in alignment and near contact with coating roller 42. The adhesive is then transferred by roller 88 to the crown portions 60 of web 24. An additional advantage is that roller 88 is made of steel or the like and will be less affected by continuous contact with crown portions 60 whereas the elastomeric covering 46 of roll 42 would be subject to rapid wear if used to transfer the adhesive directly to the web.

To control the thickness ofthe adhesive film, the eccentric mechanism 52 is adjusted to move the pressure roller 48 toward the coating roller 42 so that the embossed peripheral surface 50 of coating roller 48 deforms the elastomeric surface 46 on coating roller 42, as is illustrated in FIGURE 2. The elastomeric surface 46 is preferably formed of a resilient material that will bulge and partially fill the recessed portions 72 in the embossed surface 50 of pressure roller 48. With the elastomeric material partially filling the recesses 72 in the pressure roller 48, the protuberances 84 in the thin film 80 have a height less than the depth of the recessed portions 72. The height of the protuberances 84 on the thin film 80 is substantially equal to the depth of the recesses 72 less the dimension of the resilient elastomeric material that bulges or protrudes into the recesses 72 due to the relative position of rollers 48 and 42 to each other. The protuberances 84 on the thin film 8 0 are gradually flattened out and flow into the recesses 82 to form an extremely thin film having a thickness of be tween 0.005 inch and 0.001 inch. With the film thickness control means above described, it is now possible to control accurately the thickness of the film of adhesive that is transferred to the crown portions of the corrugated web.

It should be understood that suitable drive means may be provided for the rollers 42, 48 and 88 and means provided to drive the rollers at differing velocities. The pattern of the embossed surface of the pressure roller may vary depending on the thickness of the film desired and on the physical characteristics of the adhesive used. Although the apparatus has been described for applying adhesive to a corrugated web having a liner bonded thereto, it should be understood that the apparatus will work equally well in applying the first liner to the flutes or corrugations of the corrugated web. The adhesive applicator above described may also be used for applying succeeding laminations to laminated paperboard and may also be used in continuously applying the new adhesives such as poly-vinyl alcohol and starch emulsions in thicknesses of between 0.005 inch and 0.001 inch.

According to the provisions of the patent statutes, the principle, preferred construction, and mode of operation of the invention have been explained, and what is now' considered to represent its best embodiment has been: illustrated and described. However, it should be under-- stood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically: illustrated and described.

I claim:

1. Apparatus for applying a thin coating of a liquid adhesive to the surface of a corrugated web to make corrugated board comprising,

a transfer roller rotatably mounted adjacent to said surface,

a coating roller rotatably mounted in juxtaposition with said transfer roller,

a pressure roller rotatably mounted in juxtaposition with said coating roller, said rollers having their axes in substantially the same plane,

said coating roller having a resilient peripheral surface,

said pressure roller having a rigid embossed peripheral surface defining a plurality of recesses therein,

said transfer roller having a relatively smooth metallic surface,

a container for said liquid adhesive positioned below said coating roller and said pressure roller,

said coating roller having its lower portion positioned to be submerged in said adhesive so that upon rotation of said coating roller an uneven film of said adhesive is picked up by said coating roller,

said pressure roller positioned with said embossed peripheral surface contacting said coating roller resilient peripheral surface and forming a nip between said rollers,

said pressure roller arranged upon contact with said coating roller with said nip to squeeze said uneven film of adhesive into a thin film having a surface of substantially the same configuration as said pressure roller embossed peripheral surface,

said coating roller arranged upon contact with said transfer roller to transfer said thin film of adhesive from said coating roller to said transfer roller, and

said transfer roller operable to transfer said thin film of said adhesive onto said surface.

2. Apparatus for applying a continuous film of adhesive having a thickness of about 0.001 inch and 0.005 inch to the crown portion of a continuously moving corrugated web comprising,

a transfer roller rotatably mounted in transverse relation to the direction of travel of said continuously moving corrugated web,

a coating roller rotatably mounted in juxtaposition with said transfer roller,

a pressure roller rotatably mounted in juxtaposition with said coating roller, the axes of said coating roller and said pressure roller bring substantially the same horizontal plane and the axes of said transfer roller being in a plane positioned above the axes of said coating roller and said pressure roller,

said pressure roller having a rigid embossed peripheral surface with a plurality of recessed portions therein having a pre-selected depth and a plurality of protuberances arranged between the adjacent recesses,

said coating roller having a resilient peripheral surface formed from said elastomeric material,

a rider roller positioned above said continuously mov ing web and operable to urge said web crowned portions into abutting relation with the peripheral surface of said transfer roller,

means to urge said rider roller downwardly into abutting relation with the top surface of the continuously moving web and arranged to urge the crown portions of the continuously moving Web against the peripheral surface of said transfer roller,

a container for a bath of liquid adhesive positioned below said coating roller with the lower portion of said coating roller positioned to be submerged in said adhesive bath so that upon rotation of said coating roller said resilient peripheral surface picks up an uneven film of liquid adhesive from said bath,

said pressure roller positioned with said embossed peripheral surface contacting said coating roller resilient peripheral surface and forming a nip therebetween,

said pressure roller arranged to contact said coating roller at said nip and squeeze said uneven film of liquid adhesive on said coating roller into a thin film,

adhesive film thickness control means operable to move said pressure roller toward said coating roller to thereby deform said resilient peripheral surface on said coating roller by said rigid embossed peripheral surface of said pressure roller to urge portions of said peripheral surface into said recesses of said embossed peripheral surface and thereby displace portions of said liquid adhesive in said recesses of said embossed peripheral surface and squeeze said uneven film of adhesive into a thin adhesive film with an embossed surface having a similar configuration to the embossed surface of said pressure roller peripheral surface with the height of the protuberances in said film being less than the depth of the recesses in the pressure roller embossed peripheral surface,

said coating roller operable to convey said thin film of adhesive from said nip to said transfer roller and transfer said thin film of adhesive from said coating roller to said transfer roller, and

said transfer roller operable to convey said thin film of adhesive from said coating roller to the crown portions of said continuously moving web positioned thereabove and transfer said continuous film of adhesive having a thickness of between 0.005 inch and 0.001 inch to the crown portions of said continuously moving web.

References Cited by the Examiner UNITED STATES PATENTS 2,293,691 8/1942 Harrigan 118-249 2,589,966 3/1952 Rullo 118249 3,016,874 1/1962 Shields 118-262 3,037,451 6/ 1962 Davis.

3,046,935 7/1962 Wilson.

3 CHARLES A. WILLMUTH, Primary Examiner.

L. G. MACHLIN, Assistant Examiner. 

1. APPARATUS FOR APPLYING A THIN COATING OF A LIQUID ADHESIVE TO THE SURFACE OF A CORRUGATED WEB TO MAKE CORRUGATED BOARD COMPRISING, A TRANSFER ROLLER ROTATABLY MOUNTED ADJACENT TO SAID SURFACE, A COATING ROLLER ROTATABLY MOUNTED IN JUXTAPOSITION WITH SAID TRANSFER ROLLER, A PRESSURE ROLLER ROTATABLY MOUNTED IN JUXTAPOSITION WITH SAID COATING ROLLER, SAID ROLLERS HAVING THEIR AXES IN SUBSTANTIALLY THE SAME PLANE, SAID COATING ROLLER HAVING A RESILIENT PERIPHERAL SURFACEM SAID PRESSURE ROLLER HAVING A RIGID EMBOSSED PERIPHERAL SURFACE DEFINING A PLURALITY OF RECESSES THEREIN, SAID TRANSFER ROLLER HAVING A RELATIVELY SMOOTH METALLIC SURFACE, A CONTAINER FOR SAID LIQUID ADHESIVE POSITIONED BELOW SAID COATING ROLLER AND SAID PRESSURE ROLLER, SAID COATING ROLLER HAVING ITS LOWER PORTION POSITIONED TO BE SUBMERGED IN SAID ADHESIVE SO THAT UPON ROTATION OF SAID COATING ROLLER AN UNEVEN FILM OF SAID ADHESIVE IS PICKED UP BY SAID COATING ROLLER, SAID PRESSURE ROLLER POSITIONED WITH SAID EMBOSSED PERIPHERAL SURFACE CONTACTING SAID COATING ROLLER RESILIENT PERIPHERAL SURFACE AND FORMING A NIP BETWEEN SAID ROLLERS, SAID PRESSURE ROLLER ARRANGED UPON CONTACT WITH SAID COATING ROLLER WITH SAID NIP TO SQUEEZE SAID UNEVEN FILM OF ADHESIVE INTO A THIN FILM HAVING A SURFACE OF SUBSTANTIALLY THE SAME CONFIGURATION AS SAID PRESSURE ROLLER EMBOSSED PERIPHERAL SURFACE, SAID COATING ROLLER ARRANGED UPON CONTACT WITH SAID TRANSFER ROLLER TO TRANSFER SAID THIN FILM OF ADHESIVE FROM SAID COATING ROLLER TO SAID TRANSFER ROLLER, AND SAID TRANSFER ROLLER OPERABLE TO TRANSFER SAID THIN FILM OF SAID ADHESIVE ONTO SAID SURFACE. 